js中获取map的长度

var length  = Object.keys(map).length ;

  js java

var map = {};// Map map = new HashMap();

map[key] = value;// map.put(key, value);

var value = map[key];// Object value = map.get(key);

var has = key in map;// boolean has = map.containsKey(key);

delete map[key];// map.remove(key);

// 遍历  

for(key in map){  

    alert(key + map[key]);  

}